Our findings suggest that the Mediterranean diet results in similar weight loss and cardiovascular risk factor level reduction as comparator diets in overweight or obese individuals trying to lose weight.

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A wide variety of diets are available to promote weight loss and improve cardiovascular risk factors, such as lipid levels, blood pressure, and glycemia. Among them, 4 are particularly popular among North Americans. Millions of copies of Atkins, South Beach (SB), and Zone instructional books have been sold, [1][2][3] and over a million Weight Watchers (WW) members attend its weekly group meetings globally. 4 These diets contribute to a North American weight loss market estimated at >$66 billion for 2013. 5 Editorial see p 809Each diet has its own philosophy and macronutrient targets. Atkins is a 4-phase diet based on very low carbohydrate intake, with unlimited protein and fat consumption.1 SB is a 3-phase modified low-carbohydrate high-protein diet. It focuses on controlling carbohydrate intake, as well as eating lean proteins, mono-or polyunsaturated fats, and low-glycemic index carbohydrates.2 WW is a food, physical activity, and behavior modification plan that uses a personalized points system to provide caloric intake restriction and weekly group sessions led by plan graduates.6 Zone is a low-carbohydrate diet that recommends the consumption of low-fat proteins, low-glycemic load carbohydrates, and small amounts of good fat (eg, olive oil, avocado). 3The efficacy of these 4 popular commercial diets has been examined in several randomized controlled trials (RCTs), both comparing them to usual care and to each other. However, they provided heterogeneous results. Despite their popularity and their substantial contribution to a billion-dollar industry, the efficacy of these diets in promoting sustained weight loss and improving cardiovascular risk factors remains unclear. Our objective was to examine the efficacy of these 4 diets Background-We conducted a systematic review to examine the efficacy of the Atkins, South Beach, Weight Watchers (WW), and Zone diets, with a particular focus on sustained weight loss at ≥12 months. Methods and Results-We systematically searched MEDLINE, EMBASE, and the Cochrane Library of Clinical Trials to identify randomized controlled trials (RCTs) published in English with follow-up ≥4 weeks that examined the effects of these 4 popular diets on weight loss and cardiovascular risk factors. We identified 12 RCTs (n=2559) with follow-up ≥12 months: 10 versus usual care (5 Atkins, 4 WW, and 1 South Beach) and 2 head-to-head (1 of Atkins, WW, and Zone, and 1 of Atkins, Zone, and control). At 12 months, the 10 RCTs comparing popular diets to usual care revealed that only WW was consistently more efficacious at reducing weight (range of mean changes: −3.5 to −6.0 kg versus −0.8 to −5.4 kg; P<0.05 for 3/4 RCTs). However, the 2 head-to-head RCTs suggest that Atkins (range: −2.1 to −4.7 kg), WW (−3.0 kg), Zone (−1.6 to −3.2 kg), and control (−2.2 kg) all achieved modest long-term weight loss. Twenty-four-month data suggest that weight lost with Atkins or WW is partially regained over time. in promoting weight loss and improving cardiovascular risk factors (ie, anthropometric measures, lipid...